1. Field of the Invention
The present invention relates to a semiconductor module and an electronic component, and specifically, to a semiconductor module that is small and capable of mounting semiconductor chips in high density and that can be mounted in high density onto another electronic component, and an electronic component having such semiconductor module mounted thereon.
2. Description of the Background Art
FIG. 31 is a front view showing an example of a memory module structure of a conventional semiconductor module, and FIG. 32 is a plan view thereof. On a surface side and an underside of a mounting substrate 101, semiconductor packages 104 and 124 are mounted. This mounting substrate 101 is connected to another electronic component by an external lead 107 connected to an interconnection pattern (not shown) provided on mounting substrate 101. Semiconductor package 104 has a semiconductor chip sealed by resin, and is connected to an interconnection pattern on mounting substrate 101 via external leads 103 and 123. Another example of an electronic component having one layer of memory module 110 mounted on each side is a mother substrate 150 as shown in FIG. 33. In FIG. 33, external leads 107 for memory modules 110a, 110b, and 110c are connected to an interconnection pattern (not shown) of mother substrate 150. Thus, high packaging density could be achieved by disposing semiconductor packages 104 and 124 in two layers on mounting substrate 101.
Higher levels of smaller scale, higher density memory modules to be mounted on a portable telephone, portable terminal equipment or the like are constantly required along with the advances of the information technology oriented society. It has become difficult to satisfy the demand for such smaller scale, higher density memory modules merely by improving upon the memory module having a structure shown in FIGS. 31 to 33. Thus, in order to achieve higher density in the memory capacity of a memory module, for instance, a memory module as shown in FIG. 34 has been disclosed (Japanese Patent Laying-Open No. 4-276649). According to this memory module 110, three semiconductor packages 104a, 104b, and 104c are mounted on a single side so that the memory capacity per unit area of memory module 110 can be made higher in density than that of the memory module shown in FIGS. 31 to 33.
Until now, however, the approach of high density packaging involved achieving high density in the memory capacity only within memory module 110 so that it lacked the viewpoint of effecting high density packaging with respect to disposition of memory module 110 to mother substrate 150. In other words, it was never attempted to reduce the area per memory module on mother substrate 150. For improvement, it is desirable to dispose a memory module on a mother substrate in an area-efficient manner so as to allow mounting of one extra memory module in addition to what was conventionally provided, for instance. Such efficient disposition, when implemented, would greatly contribute to achieving higher density in the memory capacity. As shown in FIG. 33, in a conventional memory module having semiconductor packages mounted in multiple layers, memory module 110 is mounted on mother substrate 150 using external lead 107 of the mounting substrate.
An object of the present invention is to provide a semiconductor module that achieves higher density in the semiconductor module itself on which semiconductor packages such as memory modules are provided in multiple layers and that can be mounted in high density on another electronic component such as a mother substrate, and an electronic component having such semiconductor module mounted thereon.
In addition, another object of the present invention is to provide a semiconductor module which has the characteristics of the above-described semiconductor module as well as high stability in that it is not affected by slight variation in manufacturing conditions, which allows easy reworking of defect that occurs during the production, and which can maintain high yield even during high efficiency production, and an electronic component having such semiconductor module mounted thereon.
The semiconductor module according to the present invention includes a mounting substrate having on an underside a solder ball for connecting to interconnection of another electronic component, and a plurality of semiconductor packages mounted in multiple layers on a surface side of the mounting substrate and connected to an electrode provided on the mounting substrate.
The present semiconductor module is connected to another electronic component by a solder ball provided on the underside. Thus, when mounted on another electronic component, a mother substrate, for instance, the semiconductor module only occupies a small area. Consequently, a greater number of semiconductor modules can be mounted on the mother substrate for the same area so that such arrangement greatly contributes to achieving a smaller scale, higher density packaging for a portable telephone, portable terminal equipment, or the like. The above-described semiconductor packages can be stacked with one""s top side being contact with another""s underside, or with one top side distanced from one underside. When the semiconductor packages are stacked with one""s top side being contact with another""s underside, the height of the above-described semiconductor module can be reduced so that the volume of the semiconductor module can be further reduced. As a result, further improvement in smaller scale and higher density packaging can be achieved. In the above as well as in the following description, the term xe2x80x9cconnectionxe2x80x9d signifies both an electrical connection and a mechanical connection for providing support.
In the semiconductor module according to the present invention, for instance, in the plurality of the semiconductor packages, lead nominal dimensions, which are the distances between electrodes to which lead terminals of the semiconductor packages are connected, and package heights, which are the heights between the electrodes and a semiconductor chip sealed by resin, all differ respectively.
According to this arrangement, multilayer packaging on a mounting substrate can be achieved using external leads and without using other members for mounting. Thus, the number of components can be reduced so that the manufacturing cost can be reduced.
In the semiconductor module according to the present invention, for instance, a spacer substrate is provided that has a connecting portion and an interconnection pattern and that is disposed outside of the semiconductor packages when seen in a plane, and in a semiconductor package, a lead terminal of the semiconductor package can be connected to the connecting portion of the spacer substrate.
According to this arrangement, semiconductor packages of the same dimension can be systematically disposed in multiple layers and supported without varying the package heights and the lead nominal dimensions of external leads extending from a plurality of semiconductor packages to make the heights and the dimensions differ. Thus, the need to produce many kinds of semiconductor packages having external leads of different shapes can be eliminated. As a result, it becomes possible to produce the semiconductor modules efficiently and with high yield. Moreover, the length of an external lead extending from the semiconductor package can be made shorter than the above-described semiconductor package so that strong support for the semiconductor package can be provided. Here, the connecting portion forms a terminal portion of the interconnection pattern.
In the semiconductor module according to the present invention, for instance, sub-substrates, each having an interconnection pattern and an external lead and having a smaller planar size than the mounting substrate, are provided in multiple layers on the mounting substrate, and an external lead of each of the sub-substrates is connected to an electrode of the mounting substrate, and thus the semiconductor package can be mounted on the sub-substrate.
According to this arrangement, a semiconductor package is mounted on a sub-substrate and the sub-substrate is mounted on a mounting substrate so that the process can be divided into several steps, which simplifies the packaging steps. Preferably, the external leads for the plurality of sub-substrates have varying heights and also are located in different planar positions. The semiconductor packages may be mounted on both sides of the sub-substrate, or a semiconductor package may be mounted on one side only. In addition, the semiconductor packages may or may not make contact with one another, or the semiconductor package and a surface of a sub-substrate may or may not make contact. When the semiconductor packages make contact with one another, or the semiconductor package and a surface of the sub-substrate make contact, the height of the semiconductor module can be reduced so that smaller scale and higher density packaging can be effectively achieved.
In the semiconductor module according to the present invention, for instance, sub-substrates, each having an interconnection pattern and a through hole and having a smaller planar size than the mounting substrate, are provided in multiple layers on the mounting substrate by being supported by a contact pin that passes through the through hole, and the contact pin is connected to the interconnection pattern of the sub-substrate via the through hole and connected to an electrode of the mounting substrate, and thus the semiconductor package can be mounted on the sub-substrate.
According to this arrangement, interconnection patterns of the sub-substrates disposed in multiple layers can be easily connected together using a plurality of contact pins. Thus, it becomes possible to perform the packaging steps efficiently and with high yield.
In the semiconductor module according to the present invention, for instance, two standing wall-like sub-substrates are provided that are disposed such that they intersect the mounting substrate and they face one another, the standing wall-like sub-substrates each have an interconnection pattern and a through hole into which a lead terminal is to be inserted, a standing wall-like sub-substrate is connected by soldering to an electrode of the mounting substrate, the lead terminal of the semiconductor package is inserted into the through hole, and thus the semiconductor package can be mounted.
According to this arrangement, the external leads of all semiconductor packages can be made shorter. As a result, it becomes possible to produce the semiconductor modules efficiently and with high yield. Moreover, the semiconductor packages can be supported firmly. Furthermore, by adjusting the distance between the through holes in the vertical direction, the height of the semiconductor module can be reduced. Although the external leads of the semiconductor module may be linear or curved like a gull-wing type, linear leads would simplify the manufacturing steps.
In the semiconductor module according to the present invention, for instance, a recessed portion that reduces the thickness of the mounting substrate across a range including the semiconductor packages when seen in a plane can be provided on a surface side of the mounting substrate.
According to this arrangement, by having a semiconductor package received in the recessed portion, the semiconductor package is mounted on the surface side of the mounting substrate with the thickness of the semiconductor package overlapping that of the mounting substrate. Thus, the thickness of the semiconductor module becomes thinner, and smaller scale and higher density packaging can be further achieved. Moreover, the semiconductor package received in the recessed portion need not be completely received in the recessed portion in its entire thickness, but may partially protrude.
In the semiconductor module according to the present invention, for instance, a semiconductor package can also be mounted on the underside and be connected to an electrode provided on the underside.
According to this arrangement, a semiconductor package can be mounted not only on the surface side but on the underside of the mounting substrate as well. For instance, when the semiconductor package is connected to an electrode of the interconnection pattern of the mounting substrate via external leads, a long external lead is required for the outermost layer of the semiconductor packages in which many layers of semiconductor packages are stacked. As in this arrangement, however, when semiconductor packages are disposed on both sides, the number of layers can be reduced so that the external lead for the semiconductor package of the outermost layer need not be made extremely long.
In the semiconductor module according to the present invention, for instance, a recessed portion that reduces the thickness of the mounting substrate across a range including the semiconductor packages when seen in a plane is provided on an underside of the mounting substrate, and the semiconductor package disposed on the underside can be disposed in the recessed portion.
According to this arrangement, by having a semiconductor package received in the recessed portion, the semiconductor packages can be mounted not only on the surface side but also on the underside of the mounting substrate without causing a problem to the connection to the mother substrate via a solder ball. In this case, it is not necessary for the semiconductor package to be entirely received within the recessed portion, and the semiconductor package may protrude by about the height of a solder ball as long as it does not obstruct the connection via the solder ball provided on the underside. Since the semiconductor package is mounted such that it overlaps the thickness of the mounting substrate, the thickness of the semiconductor module becomes thinner, and smaller scale and higher density packaging can be further achieved.
In the semiconductor module according to the present invention, for instance, a spacer substrate having an interconnection pattern and a solder ball is disposed on the underside of the mounting substrate in a location outside of the semiconductor package located on the underside when seen in a plane, and the semiconductor package disposed on the underside can be disposed between spacer substrates.
According to this arrangement, without reducing the thickness of the mounting substrate to form the recessed portion, the recessed portion can be easily formed by spacer substrates. Thus, the semiconductor packages can be disposed on the surface side and the underside without reducing the rigidity and the like of the mounting substrate.
In the semiconductor module according to the present invention, for instance, the spacer substrate can be connected to the mounting substrate by a solder material.
According to this arrangement, the spacer substrate having a solder ball can be mounted on the mounting substrate using the solder material. Thus, the semiconductor module can be mounted easily with small occupied area to the interconnection pattern of the mother substrate or the like.
In the semiconductor module according to the present invention, for instance, the solder material is a solder ball attached to the mounting substrate, and the spacer substrate having the solder ball can be connected to the mounting substrate via the solder ball.
According to this arrangement, using the mounting substrate having a solder ball on its underside, a recessed portion can be easily formed on the underside, and the semiconductor package can be disposed in the recessed portion. Thus, there is no need to increase the number of different kinds of the mounting substrates so that the inventory can be reduced.
In the semiconductor module according to the present invention, a dummy solder material forming a junction that is not utilized for signal transmission may be provided on the underside of the mounting substrate.
By disposing and connecting the above-described dummy solder material to an electrode and the like of a mother substrate, the stress is shared and distortion is limited so that the heat cycle resistance can be improved in the junction that utilizes a solder ball with which signal transmission is performed. In addition, the above-described solder material may be a solder ball or a solder material other than the solder ball.
In the semiconductor module according to the present invention, a spacer substrate disposed on the underside of the mounting substrate is preferably a frame-like spacer substrate whose four sides are continuous so as to surround a semiconductor package disposed on the underside.
According to this arrangement, if a defect is found in the semiconductor package after the semiconductor module is mounted on the mother substrate, and the semiconductor package is to be replaced, it becomes possible easily to pull out the semiconductor module together with a spacer substrate using a removing jig. As a result, the situation where the spacer substrate alone being left on the mother substrate as it would be the case in the conventional example would no longer occur so that it becomes possible to change the defective semiconductor package alone while allowing the mother substrate to be utilized.
In the semiconductor module according to the present invention, the spacer substrate disposed on the underside of the mounting substrate can be provided with a portion that protrudes outward from the mounting substrate when seen in a plane.
According to this arrangement, when a plurality of semiconductor modules are produced simultaneously, space can be provided between the mounting substrates of the respective semiconductor modules. Consequently, when the mounting substrates are to be divided at a prescribed stage, a tip of a mounting substrate-dividing machine can be inserted in the space between the mounting substrates so as to divide and obtain the respective semiconductor modules with ease. As a result, it becomes possible to produce the semiconductor modules with high yield and high efficiency without erroneously cutting or damaging the substrate during such division.
In the semiconductor module according to the present invention, lead terminals of the semiconductor packages mounted in multiple layers on the surface side can be arranged so that one lead terminal does not overlap another when seen in a plane.
According to this arrangement, a connecting portion to a mounting substrate electrode terminal of an external lead of the semiconductor modules mounted in multiple layers can be visually inspected with ease and very high efficiency. As a result, it becomes possible to achieve significantly higher efficiency in the visual inspection process.
An electronic component according to the present invention has a semiconductor module mounted thereon, where an electrode of an interconnection pattern of the electronic component is connected to a solder ball disposed on an underside of any one of the semiconductor modules according to the present invention.
According to this arrangement, the semiconductor modules can be mounted in high density, or the area for mounting the semiconductor modules can be reduced, which leads to a smaller scale portable telephone or portable terminal equipment. A mother substrate and the like correspond to the above electronic component.